Walter, who replaced Christian Alves in the 83rd minute, latched onto Jonathan Cicero's cross and needed just one touch before rifling a shot into the bottom right corner.
Keno doubled his personal tally with a low finish and then headed in his third goal by latching on to a Mariano cross.
"To have kept the team together might turn into our big advantage," Borussia's managing director Max Eberl said.
The second half saw Sharjah take the first lead after Moroccan defender Medhi Benatia received a red card for an elbow on Sharjah playmaker Igor Coronado, who beat the goalkeeper with a curled effort, but the ball bounced off the upright and fell to midfielder Majed Surour whose diving header help Sharjah establish the lead for the first time in the tie.
The Israeli club scored the first goal in the 50th minute, with a successful penalty kick by midfielder Dan Biton, after the visitors' captain Syarhey Kislyak pushed Maccabi's Dor Peretz in the penalty area.
The paper-cutting art and the Great Wall were the symbolic cultural elements of the Zhangjiakou and Yanqing competition areas of the Beijing 2022.
The teenage footballers lost their lives late Saturday when the vehicle they were traveling in was involved in the collision in the country's southern Ashanti region.
To survive the club's crisis, Schalke turned to wage cuts, part-time work for employees, and a 30 to 40-million-euro loan from the federal state of North-Rhine Westphalia.
The 29-year-old midfielder joined the Reds with a reported fee of 20 million pounds (about 25.8 million US dollars) for four years to become the club's second signing of the summer transfer window, following Kostas Tsimikas in August.
In the women's draw, US Open quarterfinalist Elise Mertens of Belgium disposed of Chinese Taipei's Hsieh Su-Wei 6-3, 6-1.
The game between Osasuna and Getafe, which had been due to open the weekend, was moved from Friday night to Saturday afternoon, while Betis' home match against Valladolid was shifted from Monday night to Sunday evening as the result of an ongoing conflict between La Liga and the Spanish Football Federation (RFEF) over kickoff times.